Danger: Sparse Datafiles Ahead

You may have read my advice not to use sparse tempfiles on Solaris UFS, but did you know that datafiles can be sparse too? Direct and concurrent I/O is very important for Oracle database performance, so there can be a dramatic impact when database operations switch to buffered and blocking I/O.  (Eg RMAN section size … Continue reading Danger: Sparse Datafiles Ahead


Sparse UFS Tempfiles vs Direct IO

In a previous post I found that direct and concurrent I/O was disabled when restoring a certain type of backup with RMAN on UFS. A similar issue disables direct and concurrent I/O when writing to sparse tempfiles.  I haven't seen any advice on this specific issue, but it must be common because tempfiles on Solaris … Continue reading Sparse UFS Tempfiles vs Direct IO

RMAN’s Section Size and UFS Don’t Mix

When you backup your Oracle database using RMAN to create compressed backup sets, it could take a long time if you don't use multiple channels to take advantage of all of the server's CPU power. If the datafiles are vastly different in size, then the backup completion could be delayed while one channel finishes compressing … Continue reading RMAN’s Section Size and UFS Don’t Mix

UFS Fragmentation vs Oracle Datafiles

This post might interest you if your organisation has Oracle databases running on UFS. What Does UFS File Fragmentation Mean? The blocks allocated to a datafile are not contiguous in the filesystem. Why Should You Care? You may have configured your system to allow 1MB I/Os from database through to the OS and devices (direct … Continue reading UFS Fragmentation vs Oracle Datafiles